blocks the effect of gnrh and blocks the pituitary from secreting hormones, so one creates a prepubertal environment, or if you will, a hypogonadal state, and everything that has been stimulated by those increased hormones will stop or regress. >> mcfarland: there are different ways to administer gnrh analogues, or gnrh agonists. >> the most common historically has been to give a monthly intramuscular injection. however, there also are daily preparations that can be given either intranasally. >> mcfarland: both talia and iris started on injections of gnrh, but switched to an alternate therapy, which is a small, flexible implant placed beneath the skin that provides therapy for a year. the fda approve the implant with a recommended dose of one implant every year. this means every 12 months, the implant must be removed and replaced with a new one in order to continue therapy. essentially, the implant is a small medication-filled tube that is surgically implanted into the child's arm. >> the tube is designed to have tiny pores in the walls to allow a steady diffusion of the medicine for up to one year.